[D66] [JD: 12] Calender reform - britannica.com

[R.O.]

https://www.britannica.com/science/calendar/Calendar-reform-since-the-mid-18th-century


  The Mexican (Aztec) calendar
  <https://www.britannica.com/topic/Aztec-calendar>

The calendar of the Aztecs <https://www.britannica.com/topic/Aztec> was 
derived from earlier calendars in the Valley of Mexico and was basically 
similar to that of the Maya. The ritual day 
<https://www.britannica.com/science/day> cycle was called /tonalpohualli 
<https://www.britannica.com/topic/tonalpohualli>/ and was formed, as was 
the Mayan Tzolkin, by the concurrence 
<https://www.merriam-webster.com/dictionary/concurrence> of a cycle of 
numerals 1 through 13 with a cycle of 20 day names, many of them similar 
to the day names of the Maya. The /tonalpohualli/ could be divided into 
four or five equal parts, each of four assigned to a world quarter and a 
colour and including the centre of the world if the parts were five. To 
the Aztecs, the 13-day period defined by the day numerals was of prime 
importance, and each of 20 such periods was under the patronage of a 
specific deity. A similar list of 20 deities was associated with 
individual day names, and, in addition, there was a list of 13 deities 
designated as Lords of the Day, each accompanied by a flying creature, 
and a list of nine deities known as Lords of the Night. The lists of 
deities vary somewhat in different sources. They were probably used to 
determine the fate of the days by the Tonalpouhque, who were priests 
trained in calendrical divination. These priests were consulted as to 
lucky days whenever an important enterprise was undertaken or when a 
child was born. Children were often named after the day of their birth; 
and tribal gods, who were legendary heroes of the past, also bore 
calendar names.

The Aztec year <https://www.britannica.com/science/year> of 365 days was 
also similar to the year of the Maya, though probably not synchronous 
with it. It had 18 named months of 20 days each and an additional five 
days, called /nemontemi/, which were considered to be very unlucky. 
Though some colonial historians mention the use of intercalary days, in 
Aztec annals there is no indication of a correction in the length of the 
year. The years were named after days that fall 
<https://www.britannica.com/science/autumn-season> at intervals of 365 
days, and most scholars believe that these days held a fixed position in 
the year, though there appears to be some disagreement as to whether 
this position was the first day, the last day of the first month 
<https://www.britannica.com/science/month>, or the last day of the last 
month. Since 20 and 365 are both divisible by five, only four day 
names—Acatl (Reed), Tecpatl (Flint), Calli 
<https://www.merriam-webster.com/dictionary/Calli> (House), and Tochtli 
(Rabbit)—figure in the names of the 52 years that form a cycle with the 
/tonalpohualli/. The cycle begins with a year 2 Reed and ends with a 
year 1 Rabbit, which was regarded as a dangerous year of bad omen. At 
the end of such a cycle, all household utensils and idols were discarded 
and replaced by new ones, temples were renovated, and human sacrifice 
<https://www.britannica.com/topic/human-sacrifice> was offered to the 
Sun <https://www.britannica.com/place/Sun> at midnight on a mountaintop 
as people awaited a new dawn.

The year served to fix the time of festivals, which took place at the 
end of each month. The new year was celebrated by the making of a new 
fire, and a more elaborate ceremony was held every four years, when the 
cycle had run through the four day names. Every eight years was 
celebrated the coincidence of the year with the 584-day period of the 
planet Venus <https://www.britannica.com/place/Venus-planet>, and two 
52-year cycles formed “One Old Age,” when the day cycle, the year, and 
the period of Venus all came together. All these periods were noted also 
by the Maya.

Where the Aztecs differed most significantly from the Maya was in their 
more primitive number system and in their less precise way of recording 
dates. Normally, they noted only the day on which an event occurred and 
the name of the current year. This is ambiguous 
<https://www.merriam-webster.com/dictionary/ambiguous>, since the same 
day, as designated in the way mentioned above, can occur twice in a 
year. Moreover, years of the same name recur at 52-year intervals, and 
Spanish colonial annals often disagree as to the length of time between 
two events. Other discrepancies in the records are only partially 
explained by the fact that different towns started their year with 
different months. The most widely accepted correlation of the calendar 
of Tenochtitlán with the Christian Julian calendar 
<https://www.britannica.com/science/Julian-calendar> is based on the 
entrance of Spanish conquistador Hernán Cortés 
<https://www.britannica.com/biography/Hernan-Cortes> into that city on 
November 8, 1519, and on the surrender of Cuauhtémoc 
<https://www.britannica.com/biography/Cuauhtemoc> on August 
<https://www.merriam-webster.com/dictionary/August> 13, 1521. According 
to this correlation, the first date was a day 8 Wind, the ninth day of 
the month Quecholli, in a year 1 Reed, the 13th year of a cycle.

The Mexicans, as all other Mesoamericans, believed in the periodic 
destruction and re-creation of the world. The “Calendar Stone 
<https://www.britannica.com/topic/calendar-stone>” in the Museo Nacional 
de Antropología 
<https://www.britannica.com/topic/National-Museum-of-Anthropology> 
(National Museum of Anthropology) in Mexico City 
<https://www.britannica.com/place/Mexico-City> depicts in its central 
panel the date 4 Ollin (movement), on which they anticipated that their 
current world would be destroyed by earthquake, and within it the dates 
of previous holocausts: 4 Tiger, 4 Wind, 4 Rain, and 4 Water.

Aztec calendar stone; in the National Museum of Anthropology, Mexico 
City. The calendar, discovered in 1790, is a basaltic monolith. It 
weighs approximately 25 tons and is about 12 feet (3.7 metres) in 
diameter. 
<https://cdn.britannica.com/43/7043-050-DCF36CFF/Aztec-calendar-stone-National-Museum-of-Anthropology-1790.jpg>

Aztec calendar stone; in the National Museum of Anthropology, Mexico 
City. The calendar, discovered in 1790, is a basaltic monolith. It 
weighs approximately 25 tons and is about 12 feet (3.7 metres) in diameter.
Courtesy of the Museo Nacional de Antropología, Mexico City; photograph, 
Mexican Ministry of Tourism


    Peru: the Inca calendar <https://www.britannica.com/topic/Inca-calendar>

So little is known about the calendar used by the Incas 
<https://www.britannica.com/topic/Inca> that one can hardly make a 
statement about it for which a contrary opinion cannot be found. Some 
workers in the field even assert that there was no formal calendar but 
only a simple count of lunations. Since no written language was used by 
the Incas, it is impossible to check 
<https://www.britannica.com/topic/check-finance> contradictory 
statements made by early colonial chroniclers. It was widely believed 
that at least some of the quipu 
<https://www.britannica.com/technology/quipu> (/khipu/) of the Incas 
contained calendrical notations.

Felipe Guamán Poma de Ayala: El primer nueva corónica y buen gobierno, 
depiction of an Inca bookkeeper using a quipu 
<https://cdn.britannica.com/04/3604-050-CFDB193D/Bookkeeper-rendering-accounts-Inca-ruler-Topa-Yupanqui.jpg>

Felipe Guamán Poma de Ayala: /El primer nueva corónica y buen gobierno/, 
depiction of an Inca bookkeeper using a quipu 
<https://cdn.britannica.com/04/3604-050-CFDB193D/Bookkeeper-rendering-accounts-Inca-ruler-Topa-Yupanqui.jpg> 

Bookkeeper (right) rendering accounts to the Inca ruler Topa Inca 
Yupanqui. The contents of the storehouses (foreground and background) 
are recorded on the bookkeeper's quipu of knotted strings. Drawing by 
Felipe Guamán Poma de Ayala from /El primer nueva corónica y buen gobierno/.
Courtesy, Library Services Department, American Museum of Natural 
History, New York City (Neg. No. 321546)

Most historians agree that the Incas had a calendar based on the 
observation of both the Sun and the Moon 
<https://www.britannica.com/place/Moon>, and their relationship to the 
stars. Names of 12 lunar months are recorded, as well as their 
association with festivities of the agricultural cycle; but there is no 
suggestion of the widespread use of a numerical system for counting 
time, although a quinary decimal system, with names of numbers at least 
up to 10,000, was used for other purposes. The organization of work on 
the basis of six weeks <https://www.britannica.com/science/week> of nine 
days suggests the further possibility of a count by triads that could 
result in a formal month of 30 days.

A count of this sort was described by German naturalist and explorer 
Alexander von Humboldt 
<https://www.britannica.com/biography/Alexander-von-Humboldt> for a 
Chibcha <https://www.britannica.com/topic/Chibcha> tribe living outside 
of the Inca empire, in the mountainous region of Colombia 
<https://www.britannica.com/place/Colombia>. The description is based on 
an earlier manuscript by a village priest, and one authority has 
dismissed it as “wholly imaginary,” but this is not necessarily the 
case. The smallest unit of this calendar was a numerical count of three 
days, which, interacting with a similar count of 10 days, formed a 
standard 30-day “month.” Every third year was made up of 13 moons, the 
others having 12. This formed a cycle of 37 moons, and 20 of these 
cycles made up a period of 60 years, which was subdivided into four 
parts and could be multiplied by 100. A period of 20 months is also 
mentioned. Although the account of the Chibcha system cannot be accepted 
at face value, if there is any truth in it at all it is suggestive of 
devices that may have been used also by the Incas.

In one account, it is said that the Inca Viracocha 
<https://www.britannica.com/topic/Viracocha> established a year of 12 
months, each beginning with the New Moon 
<https://www.britannica.com/topic/New-Moon-Jewish-festival>, and that 
his successor, Pachacuti 
<https://www.britannica.com/biography/Pachacuti-Inca-Yupanqui>, finding 
confusion in regard to the year, built the sun towers in order to keep a 
check on the calendar. Since Pachacuti reigned less than a century 
before the conquest, it may be that the contradictions and the 
meagreness of information on the Inca calendar are due to the fact that 
the system was still in the process of being revised when the Spaniards 
first arrived.

Tatiana Proskouriakoff 
<https://www.britannica.com/contributor/Tatiana-Proskouriakoff/2376>

Despite the uncertainties, further research has made it clear that at 
least at Cuzco <https://www.britannica.com/place/Cuzco>, the capital 
city of the Incas, there was an official calendar of the sidereal–lunar 
type, based on the sidereal month of 27 ^1 /_3 days. It consisted of 328 
nights (12 × 27 ^1 /_3 ) and began on June 8/9, coinciding with the 
heliacal rising (the rising just after sunset) of the Pleiades; it ended 
on the first Full Moon after the June solstice (the winter solstice 
<https://www.britannica.com/science/winter-solstice> for the Southern 
Hemisphere). This sidereal–lunar calendar fell short of the solar year 
by 37 days, which consequently were intercalated. This intercalation 
<https://www.britannica.com/science/intercalation>, and thus the place 
of the sidereal–lunar within the solar year, was fixed by following the 
cycle of the Sun as it “strengthened” to summer 
<https://www.britannica.com/science/summer-season> (December) solstice 
<https://www.britannica.com/science/solstice> and “weakened” afterward, 
and by noting a similar cycle in the visibility of the Pleiades.

Tatiana Proskouriakoff 
<https://www.britannica.com/contributor/Tatiana-Proskouriakoff/2376>Colin 
Alistair Ronan 
<https://www.britannica.com/contributor/Colin-Alistair-Ronan/2514>


    North American Indian
    <https://www.britannica.com/topic/American-Indian> time counts

No North American Indian tribe had a true calendar—a single integrated 
<https://www.merriam-webster.com/dictionary/integrated> system of 
denoting days and longer periods of time. Usually, intervals of time 
were counted independently of one another. The day was a basic unit 
recognized by all tribes, but there is no record of aboriginal names for 
days. A common device for keeping track of days was a bundle of sticks 
of known number, from which one was extracted for every day that passed, 
until the bundle was exhausted. Longer periods of time were usually 
counted by moons, which began with the New Moon, or conjunction of the 
Sun and Moon. Years were divided into four seasons, occasionally five, 
and when counted were usually designated by one of the seasons; e.g., a 
North American Indian might say that a certain event had happened 10 
winters ago. Among sedentary agricultural tribes, the cycle of the 
seasons was of great ritual importance, but the time of the beginning of 
the year varied. Some observed it about the time of the vernal equinox 
<https://www.britannica.com/science/vernal-equinox>, others in the fall. 
The Hopi <https://www.britannica.com/topic/Hopi> tribe of northern 
Arizona held a new-fire ceremony in November. The Creek 
<https://www.britannica.com/topic/Creek-people> ceremony, known as the 
Busk, was held late in July or in August, but it is said that each Creek 
town or settlement set its own date for the celebration.

Kiowa calendar painting of the years 1833–92 on buffalo hide, photograph 
by James Mooney, 1895. 
<https://cdn.britannica.com/36/99036-050-71FCAC1D/painting-calendar-Kiowa-buffalo-James-Mooney-photograph-1895.jpg>

Kiowa calendar painting of the years 1833–92 on buffalo hide, photograph 
by James Mooney, 1895.
"Seventeenth Annual Report of the Bureau of American Ethnology to the 
Smithsonian Institution, 1895-96," by James Mooney.

As years were determined by seasons and not by a fixed number of days, 
the correlation of moons and years was also approximate and not a 
function of a daily count. Most tribes reckoned 12 moons to a year. Some 
northern tribes, notably those of New England 
<https://www.britannica.com/place/New-England>, and the Cree 
<https://www.britannica.com/topic/Cree> tribes, counted 13. The Indians 
of the northwest coast divided their years into two parts, counting six 
moons to each part, and the Kiowa 
<https://www.britannica.com/topic/Kiowa> split one of their 12 moons 
between two unequal seasons, beginning their year with a Full Moon.

The naming of moons is perhaps the first step in transforming them into 
months. The Zuni <https://www.britannica.com/topic/Zuni> Indians of New 
Mexico <https://www.britannica.com/place/New-Mexico> named the first six 
moons of the year, referring to the remainder by colour designations 
<https://www.merriam-webster.com/dictionary/designations> associated 
with the four cardinal (horizontal) directions, and the zenith and the 
nadir. Only a few Indian tribes attempted a more precise correlation of 
moons and years. The Creeks 
<https://www.britannica.com/topic/Creek-people> are said to have added a 
moon between each pair of years, and the Haida 
<https://www.britannica.com/topic/Haida> from time to time inserted a 
“between moon” in the division of their year into two parts. It is said 
that an unspecified tribe of the Sioux 
<https://www.britannica.com/topic/Sioux> or the Ojibwa 
<https://www.britannica.com/topic/Ojibwa> (Chippewa) made a practice of 
adding a “lost moon” when 30 moons had waned.

A tally of years following an important event was sometimes kept on a 
notched stick. The best-known record commemorates 
<https://www.merriam-webster.com/dictionary/commemorates> the 
spectacular meteor shower 
<https://www.britannica.com/science/meteor-shower> (the Leonids) of 
1833. Some northern tribes recorded series of events by pictographs, and 
one such record, said to have been originally painted on a buffalo robe 
and known as the “Lone-Dog Winter Count,” covers a period of 71 years 
beginning with 1800.

Early explorers had little opportunity to learn about the calendrical 
devices of the Indians, which were probably held sacred and secret. 
Contact with Europeans and their Christian calendar 
<https://www.britannica.com/topic/church-year> doubtless altered many 
aboriginal practices. Thus, present knowledge of the systems used in the 
past may not reflect their true complexity.

Tatiana Proskouriakoff 
<https://www.britannica.com/contributor/Tatiana-Proskouriakoff/2376>

<https://subscription.britannica.com/subscribe?partnerCode=BP_House_EUR>


  The Western calendar and calendar reforms

The calendar now in general worldwide use had its origin in the desire 
for a solar calendar <https://www.britannica.com/science/solar-calendar> 
that kept in step with the seasons 
<https://www.britannica.com/science/season> and possessed fixed rules of 
intercalation <https://www.britannica.com/science/intercalation>. 
Because it developed in Western Christendom, it had also to provide a 
method for dating 
<https://www.britannica.com/science/dating-geochronology> movable 
religious feasts, the timing of which had been based on a lunar 
reckoning. To reconcile 
<https://www.merriam-webster.com/dictionary/reconcile> the lunar and 
solar schemes, features of the Roman republican calendar 
<https://www.britannica.com/science/Roman-republican-calendar> and the 
Egyptian calendar <https://www.britannica.com/science/Egyptian-calendar> 
were combined.

The Roman republican calendar was basically a lunar reckoning and became 
increasingly out of phase with the seasons 
<https://www.britannica.com/science/season> as time passed. By about 50 
bce the vernal equinox 
<https://www.britannica.com/science/equinox-astronomy> that should have 
fallen late in March <https://www.britannica.com/topic/March-month> fell 
on the Ides of May, some eight weeks later, and it was plain that this 
error would continue to increase. Moreover, the behaviour of the 
Pontifices (/see above/ The early Roman calendar 
<https://www.britannica.com/science/calendar/The-early-Roman-calendar#ref60215>) 
made it necessary to seek a fixed rule of intercalation in order to put 
an end to arbitrariness in inserting months.

In addition to the problem of intercalation, it was clear that the 
average Roman republican year of 366.25 days would always show a 
continually increasing disparity with the seasons, amounting to one 
month <https://www.britannica.com/science/month> every 30 years, or 
three months a century. But the great difficulty facing any reformer was 
that there seemed to be no way of effecting a change that would still 
allow the months to remain in step with the phases of the Moon 
<https://www.britannica.com/place/Moon> and the year with the seasons. 
It was necessary to make a fundamental break with traditional reckoning 
to devise an efficient seasonal calendar.


    The Julian calendar <https://www.britannica.com/science/Julian-calendar>

In the mid-1st century bceJulius Caesar 
<https://www.britannica.com/topic/Julius-Caesar-by-Shakespeare> invited 
astronomer Sosigenes of Alexandria 
<https://www.britannica.com/biography/Sosigenes-of-Alexandria> to advise 
him about the reform of the calendar, and Sosigenes decided that the 
only practical step was to abandon the lunar calendar 
<https://www.britannica.com/science/lunar-calendar> altogether. Months 
must be arranged on a seasonal basis, and a tropical (solar) year used, 
as in the Egyptian calendar, but with its length taken as 365 ^1 /_4 days.

To remove the immense discrepancy between calendar date and equinox, it 
was decided that the year known in modern times as 46 bce should have 
two intercalations. The first was the customary intercalation of the 
Roman republican calendar due that year, the insertion of 23 days 
following February 23. The second intercalation, to bring the calendar 
in step with the equinoxes, was achieved by inserting two additional 
months between the end of November 
<https://www.britannica.com/topic/November-month> and the beginning of 
December <https://www.britannica.com/topic/December>. This insertion 
amounted to an addition of 67 days, making a year of no less than 445 
days and causing the beginning of March 45 bce in the Roman republican 
calendar to fall <https://www.britannica.com/science/autumn-season> on 
what is still called January 1 of the Julian calendar.

Previous errors having been corrected, the next step was to prevent 
their recurrence. Here Sosigenes’ suggestion about a tropical year was 
adopted and any pretense to a lunar calendar was rejected. The figure of 
365.25 days was accepted for the tropical year, and, to achieve this by 
a simple civil reckoning, Caesar directed that a calendar year of 365 
days be adopted and that an extra day 
<https://www.britannica.com/science/day> be intercalated every fourth 
year. Since February <https://www.britannica.com/topic/February> 
ordinarily had 28 days, February 24 was the sixth day (using inclusive 
<https://www.merriam-webster.com/dictionary/inclusive> numbering) before 
the Kalendae, or beginning of March, and was known as the 
/sexto-kalendae/; the intercalary day, when it appeared, was in effect a 
“doubling” of the /sexto-kalendae/ and was called the 
/bis-sexto-kalendae/. This practice led to the term /bissextile/ being 
used to refer to such a leap year 
<https://www.britannica.com/science/leap-year-calendar>. The name leap 
year is a later connotation 
<https://www.merriam-webster.com/dictionary/connotation>, probably 
derived from the Old Norse 
<https://www.britannica.com/topic/Old-Norse-language> /hlaupa/ (“to 
leap”) and used because, in a bissextile year, any fixed festival after 
February leaps forward, falling on the second weekday from that on which 
it fell the previous year, not on the next weekday as it would do in an 
ordinary year.

Apparently, the Pontifices <https://www.britannica.com/topic/pontifex> 
misinterpreted the edict and inserted the intercalation too frequently. 
The error arose because of the Roman practice of inclusive numbering, so 
that an intercalation once every fourth year meant to them intercalating 
every three years, because a bissextile year was counted as the first 
year of the subsequent four-year period. This error continued undetected 
for 36 years, during which period 12 days instead of nine were added. 
The emperor Augustus 
<https://www.britannica.com/biography/Augustus-Roman-emperor> then made 
a correction by omitting intercalary days between 8 bce and 8 ce. As a 
consequence, it was not until several decades after its inception that 
the Julian calendar came into proper operation, a fact that is important 
in chronology <https://www.britannica.com/topic/chronology> but is all 
too frequently forgotten.

It seems that the months of the Julian calendar were taken over from the 
Roman republican calendar but were slightly modified to provide a more 
even pattern of numbering. The republican calendar months of March, May 
<https://www.britannica.com/topic/May-month>, and Quintilis 
<https://www.britannica.com/topic/July> (July 
<https://www.britannica.com/topic/July>), which had each possessed 31 
days, were retained unaltered. Although there is some doubt about the 
specific details, changes may have occurred in the following way. Except 
for October <https://www.britannica.com/topic/October-month>, all the 
months that had previously had only 29 days had either one or two days 
added. January <https://www.britannica.com/topic/January>, September 
<https://www.britannica.com/topic/September>, and November received two 
days, bringing their totals to 31, while April 
<https://www.britannica.com/topic/April>, June 
<https://www.britannica.com/topic/June>, Sextilis (August 
<https://www.britannica.com/topic/August-month>), and December received 
one day each, bringing their totals to 30. October was reduced by one 
day to a total of 30 days and February increased to 29 days, or 30 in a 
bissextile year. With the exception of February, the scheme resulted in 
months having 30 or 31 days alternately throughout the year. And in 
order to help farmers, Caesar issued an almanac 
<https://www.britannica.com/topic/almanac> showing on which dates of his 
new calendar various seasonal astronomical phenomena would occur.

These arrangements for the months can only have remained in force for a 
short time, because in 8 bce changes were made by Augustus. In 44 bce, 
the second year of the Julian calendar, the Senate proposed that the 
name of the month Quintilis be changed to Julius (July), in honour of 
Julius Caesar, and in 8 bce the name of Sextilis was similarly changed 
to Augustus (August 
<https://www.merriam-webster.com/dictionary/August>). Perhaps because 
Augustus felt that his month must have at least as many days as Julius 
Caesar’s, February was reduced to 28 days and August increased to 31. 
But because this made three 31-day months (July, August, and September) 
appear in succession, Augustus is supposed to have reduced September to 
30 days, added a day to October to make it 31 days, reduced November by 
one day to 30 days, and increased December from 30 to 31 days, giving 
the months the lengths they have today.

Several scholars, however, believe that Caesar originally left February 
with 28 days (in order to avoid affecting certain religious rites 
observed in honour of the gods of the netherworld) and added two days to 
Sextilis for a total of 31; January, March, May, Quintilis, October, and 
December also had 31 days, with 30 days for April, June, September, and 
November. The subsequent change of Sextilis to Augustus therefore 
involved no addition of days to the latter.

The Julian calendar retained the Roman republican calendar method of 
numbering the days of the month. Compared with the present system, the 
Roman numbering seems to run backward, for the first day of the month 
was known as the Kalendae, but subsequent days were not enumerated as so 
many after the Kalendae but as so many before the following Nonae 
(“nones”), the day called nonae being the ninth day before the Ides 
(from /iduare/, meaning “to divide”), which occurred in the middle of 
the month and were supposed to coincide with the Full Moon. Days after 
the Nonae and before the Ides were numbered as so many before the Ides, 
and those after the Ides as so many before the Kalendae of the next month.

It should be noted that there were no weeks in the original Julian 
calendar. The days were designated either /dies fasti/ or /dies 
nefasti/, the former being business days and days on which the courts 
were open; this had been the practice in the Roman republican calendar. 
Julius Caesar designated his additional days all as /dies fasti/, and 
they were added at the end of the month so that there was no 
interference with the dates traditionally fixed for /dies comitiales/ 
(days on which public assemblies might be convened) and /dies festi/ and 
/dies feriae/ (days for religious festivals and holy days). Originally, 
then, the Julian calendar had a permanent set of dates for 
administrative matters. The official introduction of the seven-day week 
<https://www.britannica.com/science/week> by Emperor Constantine I 
<https://www.britannica.com/biography/Constantine-I-Roman-emperor> in 
the 4th century ce disrupted this arrangement.

It appears, from the date of insertion of the intercalary month in the 
Roman republican calendar and the habit of designating years by the 
names of the consuls, that the calendar year had originally commenced in 
March, which was the date when the new consul took office. In 222 bce 
the date of assuming duties was fixed as March 15, but in 153 bce it was 
transferred to the Kalendae of January 
<https://www.britannica.com/topic/January>, and there it remained. 
January therefore became the first month of the year, and in the western 
region of the Roman Empire 
<https://www.britannica.com/place/Roman-Empire>, this practice was 
carried over into the Julian calendar. In the eastern provinces, 
however, years were often reckoned from the accession of the reigning 
emperor, the second beginning on the first New Year’s day after the 
accession; and the date on which this occurred varied from one province 
to another.

<https://subscription.britannica.com/subscribe?partnerCode=BP_House_EUR>


  The Gregorian calendar
  <https://www.britannica.com/topic/Gregorian-calendar>

The Julian calendar <https://www.britannica.com/science/Julian-calendar> 
year of 365.25 days was too long, since the correct value for the 
tropical year is 365.242199 days. This error of 11 minutes 14 seconds 
per year amounted to almost one and a half days in two centuries, and 
seven days in 1,000 years. Once again the calendar became increasingly 
out of phase with the seasons. From time to time, the problem was placed 
before church councils, but no action was taken because the astronomers 
who were consulted doubted whether enough precise information was 
available for a really accurate value of the tropical year to be obtained.

Astronomical clock from the 14th century that can be used to determine 
religious feast days until the year 2019; in the cathedral of St. John 
the Baptist, Lyon, France. 
<https://cdn.britannica.com/53/130653-050-532C1F10/clock-St-John-the-Baptist-cathedral-Lyon-2019.jpg>

Astronomical clock from the 14th century that can be used to determine 
religious feast days until the year 2019; in the cathedral of St. John 
the Baptist, Lyon, France.
© Jakez/Shutterstock.com

By 1545, however, the vernal equinox 
<https://www.britannica.com/science/vernal-equinox>, which was used in 
determining Easter <https://www.britannica.com/topic/Easter-holiday>, 
had moved 10 days from its proper date; and in December, when the 
Council of Trent <https://www.britannica.com/event/Council-of-Trent> met 
for the first of its sessions, it authorized Pope Paul III 
<https://www.britannica.com/biography/Paul-III> to take action to 
correct the error. Correction required a solution, however, that neither 
Paul III nor his successors were able to obtain in satisfactory form 
until nearly 1572, the year of election of Pope Gregory XIII 
<https://www.britannica.com/biography/Gregory-XIII>. Gregory found 
various proposals awaiting him and agreed to issue a bull that the 
Jesuit <https://www.britannica.com/topic/Jesuits> astronomer Christopher 
Clavius <https://www.britannica.com/biography/Christopher-Clavius> 
(1537–1612) began to draw up, using suggestions made by the astronomer 
and physician Luigi Lilio (also known as Aloysius Lilius; died 1576).

The papal bull /Inter gravissimas 
<https://www.britannica.com/topic/Inter-gravissimas>/ (“In the gravest 
concern”) was issued on February 24, 1582. First, in order to bring the 
vernal equinox back to March 21, the day following the Feast of St. 
Francis (that is, October 5) was to become October 15, thus omitting 10 
days. Second, to bring the year closer to the true tropical year, a 
value of 365.2422 days was accepted. This value differed by 0.0078 days 
per year from the Julian calendar reckoning, amounting to 0.78 days per 
century, or 3.12 days every 400 years. It was therefore promulgated 
<https://www.merriam-webster.com/dictionary/promulgated> that three out 
of every four centennial years should be common years, that is, not leap 
years; and this practice led to the rule that no centennial years should 
be leap years unless exactly divisible by 400. Thus, 1700, 1800, and 
1900 were not leap years, as they would have been in the Julian 
calendar, but the year 2000 was. The reform, which established what 
became known as the Gregorian calendar and laid down rules for 
calculating the date of Easter 
<https://www.britannica.com/topic/Easter-holiday>, was well received by 
such astronomers as Johannes Kepler 
<https://www.britannica.com/biography/Johannes-Kepler> and Tycho Brahe 
<https://www.britannica.com/biography/Tycho-Brahe-Danish-astronomer> and 
by the Catholic princes of Europe. Many Protestants, however, saw it as 
the work of the Antichrist <https://www.britannica.com/topic/Antichrist> 
and refused to adopt it. Eventually all of Europe, as late as 1918 in 
the case of Russia, adopted the Gregorian calendar.


    The date of Easter

Easter was the most important feast of the Christian church, and its 
place in the calendar determined the position of the rest of the 
church’s movable feasts (/see/ church year 
<https://www.britannica.com/topic/Christianity/Aspects-of-the-Christian-religion#ref67528>). 
Because its timing depended on both the Moon’s phases and the vernal 
equinox, ecclesiastical 
<https://www.merriam-webster.com/dictionary/ecclesiastical> authorities 
had to seek some way of reconciling 
<https://www.merriam-webster.com/dictionary/reconciling> lunar and solar 
calendars. Some simple form of computation, usable by nonastronomers in 
remote places, was desirable. There was no easy or obvious solution, and 
to make things more difficult there was no unanimous agreement on the 
way in which Easter should be calculated, even in a lunar calendar 
<https://www.britannica.com/science/lunar-calendar>.

Easter, being the festival of the Resurrection 
<https://www.britannica.com/topic/resurrection-religion>, had to depend 
on the dating <https://www.britannica.com/science/dating-geochronology> 
of the Crucifixion 
<https://www.britannica.com/topic/crucifixion-capital-punishment>, which 
occurred three days earlier and just before the Jewish Passover 
<https://www.britannica.com/topic/Passover>. The Passover was celebrated 
on the 14th day of Nisan, the first month 
<https://www.britannica.com/science/month> in the Jewish religious 
year—that is, the lunar month the 14th day of which falls on or next 
after the vernal equinox. The Christian churches in the eastern 
Mediterranean area celebrated Easter on the 14th of Nisan on whatever 
day of the week <https://www.britannica.com/science/week> it might fall 
<https://www.britannica.com/science/autumn-season>, but the rest of 
Christendom adopted a more elaborate reckoning to ensure that it was 
celebrated on a Sunday 
<https://www.britannica.com/topic/Sunday-day-of-week> in the Passover week.

To determine precisely how the Resurrection and Easter Day should be 
dated, reference was made to the Gospels; 
<https://www.britannica.com/topic/Gospel-New-Testament> but, even as 
early as the 2nd century ce, difficulties had arisen, because the 
synoptic Gospels (Matthew 
<https://www.britannica.com/topic/Gospel-According-to-Matthew>, Mark 
<https://www.britannica.com/topic/Gospel-According-to-Mark>, and Luke 
<https://www.britannica.com/topic/Gospel-According-to-Luke>) appeared to 
give a different date from the Gospel According to John 
<https://www.britannica.com/topic/Gospel-According-to-John> for the 
Crucifixion. This difference led to controversy that was later 
exacerbated <https://www.merriam-webster.com/dictionary/exacerbated> by 
another difficulty caused by the Jewish reckoning of a day from sunset 
to sunset. The question arose of how the evening of the 14th day should 
be calculated, and some—the Quintodecimans—claimed that it meant one 
particular evening, but others—the Quartodecimans 
<https://www.britannica.com/topic/Quartodecimanism>—claimed that it 
meant the evening before, since sunset heralded a new day. Both sides 
had their protagonists, the Eastern churches supporting the 
Quartodecimans, the Western churches the Quintodecimans. The question 
was finally decided by the Western church in favour of the 
Quintodecimans, though there is debate whether this was at the Council 
of Nicaea <https://www.britannica.com/event/First-Council-of-Nicaea-325> 
in 325 or later. The Eastern churches 
<https://www.britannica.com/topic/Eastern-Orthodoxy> decided to retain 
the Quartodeciman position, and the church in Britain, which had few 
links with European churches at this time, retained the Quartodeciman 
position until Roman missionaries arrived in the 6th century, when a 
change was made. The dating of Easter in the Gregorian calendar was 
based on the decision of the Western church, which decreed that Easter 
should be celebrated on the Sunday immediately following the (Paschal) 
Full Moon that fell on or after the vernal equinox, which they took as 
March 21. The church also ordered that if this Full Moon fell on a 
Sunday, the festival should be held seven days later.

With these provisions in mind, the problem could be broken down into two 
parts: first, devising a simple but effective way of calculating the 
days of the week for any date in the year and, second, determining the 
date of the Full Moons in any year. The first part was solved by the use 
of a letter code derived from a similar Roman system adopted for 
determining market days. For ecclesiastical use, the code gave what was 
known as the Sunday, or dominical, letter 
<https://www.britannica.com/science/dominical-letter>.

The seven letters A through G are each assigned to a day, consecutively 
from January 1 so that January 1 appears as A, January 2 as B, to 
January 7 which appears as G, the cycle then continuing with January 8 
as A, January 9 as B, and so on. Then in any year the first Sunday is 
bound to be assigned to one of the letters A–G in the first cycle, and 
all Sundays in the year possess that dominical letter. For example, if 
the first Sunday falls on January 3, C 
<https://www.britannica.com/science/coulomb> will be the dominical 
letter for the whole year. No dominical letter is placed against the 
intercalary day <https://www.britannica.com/science/leap-year-calendar>, 
February 29, but, since it is still counted as a weekday and given a 
name, the series of letters moves back one day every leap year 
<https://www.britannica.com/science/leap-year-calendar> after 
intercalation <https://www.britannica.com/science/intercalation>. Thus, 
a leap year beginning with the dominical letter C will change to a year 
with the dominical letter B on March 1; and in lists of dominical 
letters, all leap years are given a double letter notation, in the 
example just quoted, CB. It is not difficult to see what dominical 
letter or letters apply to any particular year, and it is also a 
comparatively simple matter to draw up a table of dominical letters for 
use in determining Easter Sunday. The possible dates on which Easter 
Sunday can fall are written down—they run from March 22 through April 
25—and against them the dominical letters for a cycle of seven years. 
Once the dominical letter for a year is known, the possible Sundays for 
celebrating Easter can be read directly from the table. This system does 
not, of course, completely determine Easter; to do so, additional 
information is required.

This must provide dates for Full Moons 
<https://www.britannica.com/science/full-Moon-lunar-phase> throughout 
the year, and for this a lunar cycle like the Metonic cycle 
<https://www.britannica.com/science/Metonic-cycle> was originally used. 
Tables were prepared, again using the range of dates on which Easter 
Sunday could appear, and against each date a number from one through 19 
was placed. This number indicated which of the 19 years of the lunar 
cycle would give a Full Moon on that day. From medieval 
<https://www.merriam-webster.com/dictionary/medieval> times these were 
known as golden numbers 
<https://www.britannica.com/science/golden-number>, possibly from a name 
used by the Greeks for the numbers on the Metonic cycle or because gold 
is the colour used for them in manuscript calendars.

The system of golden numbers was introduced in 530, but the numbers were 
arranged as they should have been if adopted at the Council of Nicaea 
two centuries earlier; and the cycle was taken to begin in a year when 
the New Moon <https://www.britannica.com/topic/New-Moon-Jewish-festival> 
fell on January 1. Working backward, chronologers found that this date 
had occurred in the year preceding 1 ce, and therefore the golden number 
<https://www.britannica.com/science/golden-number> for any year is found 
by adding one to the year and dividing that sum by 19. The golden number 
is the remainder or, if there is no remainder, 19.

To compute the date of Easter, the medieval chronologer computed the 
golden number for the year and then consulted his table to see by which 
date this number lay. Having found this date, that of the first Full 
Moon after March 20, he consulted his table of dominical letters and saw 
the next date against which the dominical letter for that year appeared; 
this was the Sunday to be designated Easter. The method, modified for 
dropping centennial leap years as practiced in the Gregorian calendar, 
is still given in the English prayer book, although it was officially 
discarded when the Gregorian calendar was introduced.

The system of golden numbers was eventually rejected because the 
astronomical Full Moon could differ by as much as two days from the date 
they indicated. It was Lilius who had proposed a more accurate system 
based on one that had already been in use unofficially while the Julian 
calendar was still in force. Called the epact—the word is derived from 
the Greek /epagein/, meaning “to intercalate”—this was again a system of 
numbers concerned with the Moon’s phases, but now indicating the age of 
the Moon on the first day of the year, from which the age of the Moon on 
any day of the year may be found, at least approximately, by counting, 
using alternately months of 29 and 30 days.

The epact as previously used was not, however, completely accurate 
because, like the golden number, it had been based on the Metonic cycle. 
This 19-year cycle was in error, the discrepancy amounting to eight days 
every 2,500 years. A one-day change on certain centennial years was then 
instituted by making the computed age of the Moon one day later seven 
times, at 300-year intervals, and an eighth time after a subsequent 400 
years. This operation was known as the lunar correction, but it was not 
the only correction required; there was another.

Because the Gregorian calendar used a more accurate value for the 
tropical year than the Julian calendar and achieved this by omitting 
most centennial leap years, Clavius 
<https://www.britannica.com/biography/Christopher-Clavius> decided that, 
when the cycle of epacts reached an ordinary centennial year, the number 
of the epact should be reduced by one; this reduction became known as 
the solar correction.

One advantage of the epact number was that it showed the age of the Moon 
on January 1 and so permitted a simple calculation of the dates of New 
Moon and Full Moon for the ensuing year. Another was that it lent itself 
to the construction of cycles of 30 epact numbers, each diminishing by 
one from the previous cycle, so that, when it became necessary at 
certain centennial years to shift from one cycle to another, there would 
still be a cycle ready that retained a correct relationship between 
dates and New Moons.

For determining Easter, a table was prepared of the golden numbers, one 
through 19, and below them the cycles of epacts for about 7,000 years; 
after this time, all the epact cycles are repeated. A second table was 
then drawn up, giving the dates of Easter Full Moons for different epact 
numbers. Once the epact for the year was known, the date of the Easter 
Full Moon could be immediately obtained, while consultation of a table 
of dominical letters showed which was the next Sunday. Thus, the 
Gregorian system of epacts, while more accurate than the old golden 
numbers, still forced the chronologer to consult complex astronomical 
tables.


    Adoption in various countries

The derivation of the term /style/ for a type of calendar seems to have 
originated sometime soon after the 6th century as a result of 
developments in calendar computation in the previous 200 years. In 463 
ce Victorius 
<https://www.britannica.com/biography/Victorius-of-Aquitaine> (or 
Victorinus) of Aquitaine, who had been appointed by Pope Hilarius to 
undertake calendar revision, devised the Great Paschal (i.e., Passover) 
period, sometimes later referred to as the Victorian period. It was a 
combination of the solar <https://www.britannica.com/place/Sun> cycle of 
28 years and the Metonic 19-year cycle, bringing the Full Moon 
<https://www.britannica.com/place/Moon> back to the same day of the 
month, and amounted to 28 × 19, or 532 years. In the 6th century this 
period was used by Dionysius Exiguus 
<https://www.britannica.com/biography/Dionysius-Exiguus> (Denis the 
Little) in computing the date of Easter, because it gave the day of the 
week for any day in any year, and so it also became known as the 
Dionysian period <https://www.britannica.com/science/Dionysian-period>. 
Dionysius took the year now called 532 ce as the first year of a new 
Great Paschal period and the year now designated 1 bce as the beginning 
of the previous cycle. In the 6th century it was the general belief that 
this was the year of Christ’s birth, and because of this Dionysius 
introduced the concept of numbering years consecutively through the 
Christian era. The method was adopted by some scholars but seems only to 
have become widely used after its popularization by the Venerable Bede 
of Jarrow 
<https://www.britannica.com/biography/Saint-Bede-the-Venerable> 
(673?–735), whose reputation for scholarship was very high in Western 
Christendom <https://www.britannica.com/topic/Christianity> in the 8th 
century. This system of bce/ce numbering threw into relief the different 
practices, or styles, of reckoning the beginning of the year then in 
use. When the Gregorian calendar firmly established January 1 as the 
beginning of its year, it was widely referred to as the New Style 
calendar, with the Julian the Old Style calendar. In Britain, under the 
Julian calendar, the year had first begun on December 25 and then, from 
the 14th century onward, on March 25.

Because of the division of the Eastern and Western Christian churches 
and of Protestants <https://www.britannica.com/topic/Protestantism> and 
Roman Catholics, the obvious advantages of the Gregorian calendar were 
not accepted everywhere, and in some places adoption was extremely slow. 
In France, Italy, Luxembourg, Portugal, and Spain, the New Style 
calendar was adopted in 1582, and it was in use by most of the German 
Roman Catholic states as well as by Belgium and part of the Netherlands 
by 1584. Switzerland’s change was gradual, on the other hand 
<https://www.britannica.com/science/hand-measurement>, beginning in 1583 
and being completed only in 1812. Hungary adopted the New Style in 1587, 
and then there was a pause of more than a century before the first 
Protestant countries made the transition from the Old Style calendar. In 
1699–1700, Denmark and the Dutch and German Protestant states embraced 
the New Style, although the Germans declined to adopt the rules laid 
down for determining Easter. The Germans preferred to rely instead on 
astronomical tables and specified the use of the /Tabulae Rudolphinae/ 
(1627; “Rudolphine Tables”), based on the 16th-century observations of 
Tycho Brahe 
<https://www.britannica.com/biography/Tycho-Brahe-Danish-astronomer>. 
They acceded to the Gregorian calendar rules for Easter only in 1776. 
Britain adopted the New Style in 1752 and Sweden in 1753, although the 
Swedes, because they had in 1740 followed the German Protestants in 
using their astronomical <https://www.britannica.com/science/astronomy> 
methods for determining Easter, declined to adopt the Gregorian calendar 
rules until 1844. Japan <https://www.britannica.com/place/Japan> adopted 
the New Style in 1873; Egypt adopted it in 1875; and between 1912 and 
1917 it was accepted by Albania, Bulgaria, China, Estonia, Latvia, 
Lithuania, Romania, and Turkey. The now-defunct Soviet Union 
<https://www.britannica.com/place/Soviet-Union> adopted the New Style in 
1918, and Greece in 1923.

In Britain and the British dominions, the change was made when the 
difference between the New and Old Style calendars amounted to 11 days: 
the lag was covered by naming the day after September 2, 1752, as 
September 14, 1752. There was widespread misunderstanding among the 
public, however, even though legislation authorizing the change had been 
framed to avoid injustice and financial hardship. The Alaskan territory 
retained the Old Style calendar until 1867, when it was transferred from 
Russia to the United States.

<https://subscription.britannica.com/subscribe?partnerCode=BP_House_EUR>


  Calendar reform since the mid-18th century


    The French republican calendar
    <https://www.britannica.com/science/French-republican-calendar>

In late 18th-century France, with the approach of the French Revolution 
<https://www.britannica.com/event/French-Revolution>, demands began to 
be made for a radical change in the civil calendar that would divorce it 
completely from any ecclesiastical 
<https://www.merriam-webster.com/dictionary/ecclesiastical> connections. 
The first attacks on the Gregorian calendar 
<https://www.britannica.com/topic/Gregorian-calendar> and proposals for 
reform came in 1785 and 1788, the changes being primarily designed to 
divest <https://www.merriam-webster.com/dictionary/divest> the calendar 
of all its Christian associations. After the storming of the Bastille 
<https://www.britannica.com/topic/Bastille> in July 1789, demands became 
more vociferous <https://www.merriam-webster.com/dictionary/vociferous>, 
and a new calendar, to start from “the first year of liberty,” was 
widely spoken about. In 1793 the National Convention 
<https://www.britannica.com/topic/National-Convention> appointed 
Charles-Gilbert Romme, president of the committee of public instruction, 
to take charge of the reform. Technical matters were entrusted to the 
mathematicians Joseph-Louis Lagrange 
<https://www.britannica.com/biography/Joseph-Louis-Lagrange-comte-de-lEmpire> 
and Gaspard Monge 
<https://www.britannica.com/biography/Gaspard-Monge-comte-de-Peluse> and 
the renaming of the months to the Paris deputy to the convention, 
Philippe Fabre d’Églantine 
<https://www.britannica.com/biography/Philippe-Fabre-dEglantine>. The 
results of their deliberations were submitted to the convention in 
September of the same year and were immediately accepted, it being 
promulgated <https://www.merriam-webster.com/dictionary/promulgated> 
that the new calendar should become law on October 5.

The French republican calendar 
<https://www.britannica.com/science/French-republican-calendar>, as the 
reformed system came to be known, was taken to have begun on September 
22, 1792, the day of the proclamation of the Republic and, in that year, 
the date also of the autumnal equinox 
<https://www.britannica.com/science/equinox-astronomy>. The total number 
of days in the year was fixed at 365, the same as in the Julian and 
Gregorian calendars, and this was divided into 12 months of 30 days 
each, the remaining five days at year’s end being devoted to festivals 
and vacations. These were to fall 
<https://www.britannica.com/science/autumn-season> between September 17 
and 22 and were specified, in order, to be festivals in honour of 
virtue, genius, labour, opinion, and rewards. In a leap year an extra 
festival was to be added—the festival of the Revolution. Leap years were 
retained at the same frequency as in the Gregorian calendar, but it was 
enacted that the first leap year should be year 3, not year 4 as it 
would have been if the Gregorian calendar had been followed precisely in 
this respect. Each four-year period was to be known as a /Franciade/.

The seven-day week <https://www.britannica.com/science/week> was 
abandoned, and each 30-day month was divided into three periods of 10 
days called /décades 
<https://www.britannica.com/topic/decade-French-chronology>/, the last 
day of a /décade/ being a rest day. It was also agreed that each day 
should be divided into decimal parts, but this was not popular in 
practice and was allowed to fall into disuse.

The months themselves were renamed so that all previous associations 
should be lost, and Fabre d’Églantine chose descriptive names as follows 
(the descriptive nature and corresponding Gregorian calendar dates for 
years 1, 2, 3, 5, 6, and 7 are given in parentheses):

  *
    Vendémiaire <https://www.britannica.com/topic/Vendemiaire>
    (“vintage,” September 22 to October 21),
  *
    Brumaire (“mist,” October 22 to November 20),
  *
    Frimaire (“frost,” November 21 to December 20),
  *
    Nivôse (“snow,” December 21 to January 19),
  *
    Pluviôse (“rain,” January 20 to February 18),
  *
    Ventôse (“wind,” February 19 to March 20),
  *
    Germinal (“seedtime,” March 21 to April 19),
  *
    Floréal (“blossom,” April 20 to May 19),
  *
    Prairial (“meadow,” May 20 to June 18),
  *
    Messidor (“harvest,” June 19 to July 18),
  *
    Thermidor (“heat,” July 19 to August
    <https://www.merriam-webster.com/dictionary/August> 17), and
  *
    Fructidor (“fruits,” August 18 to September 16).

The French republican calendar was short-lived, for while it was 
satisfactory enough internally, it clearly made for difficulties in 
communication abroad because its months continually changed their 
relationship to dates in the Gregorian calendar. In September 1805, 
under the Napoleonic regime, the calendar was virtually abandoned, and 
on January 1, 1806, it was replaced by the Gregorian calendar.


    Soviet calendar reforms

When Soviet Russia undertook its calendar reform in February 1918, it 
merely moved from the Julian calendar 
<https://www.britannica.com/science/Julian-calendar> to the Gregorian. 
This move resulted in a loss of 13 days, so that February 1, 1918, 
became February 14.


    Modern schemes for reform

The current calendar is not without defects, and reforms are still being 
proposed. Astronomically, it really calls for no improvement, but the 
seven-day week and the different lengths of months are unsatisfactory to 
some. Clearly, if the calendar could have all festivals and all rest 
days fixed on the same dates every year, as in the original Julian 
calendar, this arrangement would be more convenient, and two general 
schemes have been put forward—the International Fixed Calendar and the 
World Calendar.

A perpetual calendar makes it possible to find the correct day of the 
week for any date over a wide range of years. 
<https://cdn.britannica.com/55/130655-050-E22E92E4/calendar-range.jpg>

A perpetual calendar makes it possible to find the correct day of the 
week for any date over a wide range of years.
© Dan Tataru/Shutterstock.com

The International Fixed Calendar is essentially a perpetual Gregorian 
calendar, in which the year is divided into 13 months, each of 28 days, 
with an additional day at the end. Present month names are retained, but 
a new month named Sol is intercalated between June and July. The 
additional day follows December 28 and bears no designation 
<https://www.merriam-webster.com/dictionary/designation> of month date 
or weekday name, while the same would be true of the day intercalated in 
a leap year <https://www.britannica.com/science/leap-year-calendar> 
after June 28. In this calendar, every month begins on a Sunday 
<https://www.britannica.com/topic/Sunday-day-of-week> and ends on a 
Saturday <https://www.britannica.com/topic/Saturday-day>.

It is claimed that the proposed International Fixed Calendar does not 
conveniently divide into quarters for business reckoning; and the World 
Calendar <https://www.britannica.com/topic/world-calendar> is designed 
to remedy this deficiency, being divided into four quarters of 91 days 
each, with an additional day at the end of the year. In each quarter, 
the first month is of 31 days and the second and third of 30 days each. 
The extra day comes after December 30 and bears no month or weekday 
designation, nor does the intercalated leap year day that follows June 
30. In the World Calendar January 1, April 1, July 1, and October 1 are 
all Sundays. Critics point out that each month extends over part of five 
weeks, and each month <https://www.britannica.com/science/month> within 
a given quarter begins on a different day 
<https://www.britannica.com/science/day>. Nevertheless, both these 
proposed reforms seem to be improvements over the present system that 
contains so many variables.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tuxtown.net/pipermail/d66/attachments/20210306/67cbb3aa/attachment-0001.html>